Food Allergy Testing: When and Why You Use It

Food Allergy Testing: When and Why You Use It

It’s no secret that our diet plays a huge role in our health. Everything that we put in our body on a regular basis does. Combine that with a human’s obsession with food in general, and it makes for a lot of opinions about what we should and shouldn’t be eating on a regular basis.

You can find as many diets out there removing or modifying different foods as you can foods themselves. And while it’s true that certain conditions (especially autoimmune diseases) will do better with specific dietary modifications, figuring out which diets or modifications are best for each individual person is tricky.

There is a reason that certain diets like the paleo diet, or keto diet or autoimmune paleo diet are popular – because most people feel good when they take out some of the main foods (like gluten and dairy) that most of the population usually has issues with. But I’ve been doing this long enough to know that highly restrictive diets are not sustainable long term for a majority of the population. This is where food allergy testing comes in.

Food Allergy Testing: The Basics

There is a lot of controversy around food allergy testing. And rightfully so – not all food testing is created equal. Nor is it regulated equally. Food allergy or sensitivity testing is usually separated out into a few main categories: scratch testing, antibody testing and leukocyte activity testing.

Scratch testing is the most implemented food allergy testing done by conventional practitioners and allergists. This is where a doctor will scratch the surface of your skin and expose it to a food particle. After a few min (usually 15), they will measure the size of the skin reaction to the food you were exposed to. This is often done to detect severe allergies or even the potential for anaphylaxis to a food. This type of testing though only really checks your histamine (IgE) response within a short period. This test is best done to detect severe allergies or allergic reactions that may cause serious harm to a patient. It is not very sensitive for more delayed allergic reactions or sensitivities (IgG or IgA).

Antibody testing is the most commonly used blood testing for food allergies or sensitivities. This is where your blood is exposed to a number of different foods and then the amount of antibodies that you have in your blood that react to those foods are measured. There are many different types of antibodies that can be measured to foods: IgE (acute reactions), IgG (delayed reactions), IgA (local reactions). Each of these different antibodies will paint a picture to how your immune system is reacting to different foods. Elevations in blood IgE levels will often correlate with scratch testing results. Elevations in IgG or IgA levels though are more delayed reactions and so will not come up on a scratch test. These types of reactions are often called delayed phase reactions or ‘sensitivities.’ Your immune system is reacting but it depends on the quantity, frequency and duration of your exposure to the food. More on the different antibodies in future blog posts!

Leukocyte activity testing is a different kind of blood test. This is where your blood is exposed to several foods and then the reactions of your white blood cells are measured. This testing tends to be more variable in it’s results, and several labs that run this kind of testing will often recommend rotation type diets, which can be beneficial to some people.

Food Allergy Testing Pros

So what are the pros of using food allergy testing and when would we consider using it? Well for starters – let’s talk about dietary compliance. Often when we have to make big changes to our diet, it’s HARD. Many diets want you to remove several foods at one time, and that can be difficult. Especially with little or no motivation. Food allergy testing can provide a blueprint for where to start when wanting to make dietary changes. And for a lot of people it can help guide them in their decision making in terms of what they should focus on eating.

Another benefit is that food allergy testing can look at a wide variety of foods instead of a select few. Often big elimination diets want you to eliminate the most common allergens. These are gluten, dairy, soy, eggs, peanuts…etc. But it can be hard to eliminate all those foods that are in our standard American diet. I’ve seen a number of people (myself included) find that they have reactions to foods that they would have never guessed. Things like nuts, vegetables, fruits and meats. And then removing these things has shown to be beneficial when elimination diets have failed.

Food allergy testing can also give you an idea as to the degree in which you are reacting to something. With delayed reactions like IgG reactions, sometimes you can eat the food sometimes, but not all the time. If you have stronger reactions to certain foods, you’ll have an idea of how often you can eat that food or in which quantity.

Food Allergy Testing Cons

The cons of food allergy testing are what you hear mostly in the general public. First – the accuracy of food allergy testing can be questionable. But all lab testing that looks at immune activity can be variable in some degrees. Immune reactions to foods or any antigen can change daily. The goal is to use food allergy testing as a guide. Eliminations of the foods still has to be done. And then the re-challenge of the foods later on is what tells you if you are having reactions or not.

Second, food allergy testing can be expensive. A lot of these types of tests (apart from scratch tests) are not covered by insurance. Most tests will have to be paid out of pocket and can be several hundreds of dollars. Having a doctor versed in this area though can help you decide which test is right for you so you don’t spend more money than you need to.


Food allergy testing can be a helpful tool to help you figure out where to start in your diet journey. The gold standard for knowing which foods cause which reactions is ultimately elimination. But if you need some guidance or you are feeling overwhelmed about where to start, testing is a good idea.

The caveat to this is that you want a knowledgeable physician to help guide you. If you have a doctor on board that understands food allergy testing and how to utilize it, you’re in luck. If you are looking for someone to help you figure out what dietary changes are best for you, call us today! Our doctors commonly use the antibody testing to help identify food reactions. We would be happy to review this with you and discuss the ways in which this testing might benefit you.

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